Injection blow molding machine

ABSTRACT

This invention discloses an injection blow molding machine comprising a circular rotary disk rotatably mounted on the underside of a base plate, the rotary disk being connected to an intermittently rotating and driving device installed on the central portion of the base plate, the required number of hold molds also serving as a mold for molding a mouth portion of a container being molded, the hold molds being provided at regular intervals on the undersurface of the rotary disk, a clamping device for an injection mold and a clamping device for a blow mold provided at stop positions of the hold molds so that the clamping devices are located vertically above and below the base plate. The base plate holding the rotary disk is secured to the peripheral edge of the machine bed, and the interior of the machine bed is formed into a molding operating space.

FIELD OF THE INVENTION

This invention relates to a molding machine which can be used in thecase where a preform is injection molded from a synthetic resin, and theresulting preform is immediately blow molded into a thin-wall container.

BACKGROUND OF THE INVENTION

Various constructions of machines for immediately molding an injectionmolded preform into a thin-wall container such as a bottle or cup havebeen well known. Particularly, a molding machine disclosed in U.S. Pat.No. 4,105,391, that is, a molding machine comprising a machine bed, abase plate disposed above the machine bed, a rotary disk provided on theundersurface of the base plate, and a space used for molding operation,the space being provided between the base plate and the machine bed,whereby the rotatably provided rotary disk is intermittently driven tosuccessively feed injection molded preforms and blow molded products, isbeing widely used as a molding machine which can continuously carry outa series of operations of injection molding of preforms, temperaturecontrolling and stretching and blow molding.

In the above-described well known molding machine, since the rotary diskis located on the undersurface of the base plate, support points of thebase plate disposed above the machine bed are limited to the peripheraledge, and various operating portions such as injection, temperaturecontrol and blowing are provided in stop positions of neck moldsprovided in spaced apart relation on the undersurface of the rotary diskwith a clamping device, a blowing device, etc. arranged, because ofwhich the number of support points is limited to 3 to 4 points.

Therefore, it has not been possible to increase the diameter of the baseplate and rotary disk so that the neck molds provided on theundersurface of the rotary disk and the devices provided on the baseplate are made to a larger size for volume production of moldedproducts, in terms of loads. Furthermore, tie bars of the clampingdevice are used to support the base plate, there poses problems suchthat with the trend of large size of the base plate, the supportingspacing becomes prolonged, and the foundation tends to flex.

SUMMARY OF THE INVENTION

This invention has been achieved in order to solve these problems notedabove with respect to the conventional molding machine. It is an objectof this invention to provide a molding machine having novel constructionin which even if the support position of the base plate is at theperipheral edge, support points may be increased; tie bars of theclamping device need not be used to support the base plate; a largemachine may be used for volume production; and the machine may beutilized not only for injection blow molding but for injectionstretching blow molding.

For achieving the aforementioned object, the present invention isfeaturized in that a base plate having a circular rotary disk rotatablyprovided on the underside thereof is placed on the upper surface of amachine bed with the peripheral portion thereof fixed, the machine bedis interiorly provided with a molding operating space to accommodatetherein a lower clamping mechanism of each clamping device providedvertically to injection and blow molding position of the base plate, andinjection and blow molds are mounted on a lower clamping plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate an injection blow molding machine according tothis invention.

FIG. 1 is a longitudinal sectional view;

FIG. 2 is a plan view with various devices on the base plate removed;

FIG. 3 is a sectional view taken on line III--III of FIG. 2; and

FIGS. 4 to 6 are partial sectional views, respectively, showing themolding steps in order.

BEST MODE FOR EMBODYING THE INVENTION

In the drawings, reference numeral 1 designates a machine bed, 2 a baseplate and 3 a circular rotary disk.

The upper surface of the machine bed 1 is open leaving the peripheraledge portions, and the base plate 2 is placed on the upper surface ofthe machine bed. The peripheral portion of the base plate is secured tothe peripheral edge portion of the machine bed through receiving members4.

On the underside of the base plate 2 is rotatably provided the rotarydisk 3 with peripheral portions thereof held by the receiving members 4,and at four portions of the undersurface of the rotary disk 3 aremounted hold molds 5 which also serve as molds for molding a preformmouth. The rotary disk 3 is connected through a shaft 7 and an arm 8 toa driving device 6 in the form of a hydraulic pressure actuatorinstalled in the central portion on the upper surface of the base plate2. Although not shown, the rotary disk 3 is intermittently moved by 90°similar to the intermittent rotating means disclosed in U.S. Pat. No.4,105,391.

The aforesaid hold mold 5 stops at an injection operating stage A and ablow operating stage B. In the illustrated embodiment, the opposedpositions are utilized for one and the same operating stage so thatinjection molding and blow molding may be carried out simultaneously attwo locations.

In the injection operating stage A, an injection clamping device 9 isprovided vertically to the base plate 2, and in the blow molding stageB, a blow clamping device 10 is provided vertically.

The clamping device 9 comprises an upper clamping mechanism on the baseplate and a lower clamping mechanism within the machine bed. An upperfixed plate 91 and a lower fixed plate 92 in the clamping device 9 areconnected by means of two tie bars 93 which extend through the baseplate 2, and upper and lower clamping plates 94 and 95 are mountedmovably up and down on the tie bars. The upper and lower clamping plates94 and 95 are connected to rams 98 and 99 of clamping cylinders 96 and97 provided on the upper and lower fixed plates 91 and 92, respectively.Although not shown, a hydraulically-operated quick feed device isprovided over the upper fixed plate 91 and the upper clamping plate 94.

An injection core 21 positioned in a mold portion 5a of the hold mold 5from a hole formed in the base plate 2 and the rotary disk 3 is providedon the underside of the upper clamping plate 94, and an injection mold22 is mounted on the upper surface of the lower clamping plate 95.

The upper clamping mechanism of the blow clamping device 10 is designedso that the upper clamping plate 12 is inserted movably up and down intofour guide rods 11 stood upright on the base plate, and a rod 14 of theclamping cylinder 13 above the guide rod is connected to the upperclamping plate 12. A blow core 24 provided with a stretching rod 23 (seeFIG. 5), which is moved up and down by means of an air cylinder 15provided on the upper surface of the upper clamping plate 12 is mountedon the undersurface of the upper clamping plate 12, the blow core 24being positioned in the mold portion 5a from the hole formed in the baseplate 2 and the rotary disk 3 similar to the injection core 21.

The lower clamping mechanism of the blow clamping device 10 is designedso that as shown in FIGS. 1 and 3, a lower fixed plate 17 is connectedover four tie bars 16 suspended within the machine bed from the oppositeperipheral edges of the rotary disk 2, a lower clamping plate 18 isinserted into the tie bars 16 and a plurality of guide rods 16a stoodupright on the lower fixed plate 17, and a ram 20 of a clamping cylinder19 provided on the lower fixed plate 17 is connected to the undersurfaceof the lower clamping plate 18. A blow mold 25 is mounted on the lowerclamping plate 18 above the lower fixed plate 17 being suspended overthe aforesaid two blow operating stages B, B.

In the above-described molding machine, the interior of the machine bed1 is utilized as an operating space, and operations from injectionmolding of a preform to blow molding of thin-wall containers, forexample, such as cups, are carried out within the machine bed.

Injection molding is carried out by bringing injection devices 26 on themachine bed provided on opposite sides of the machine bed into nozzletouch with the injection mold 22 after clamping has been completed.Resin is injected from the injection device 26 to thereby mold a flatpreform 27 as shown in FIG. 4, and the resulting preform 27 istransported along with the hold mold 5 to the blow operating stage B byhorizontal movement of the rotary disk 3 after mold has been opened.

After completion of clamping in the blow operating stage B, the preformis stretched by means of a stretching rod 23, as shown in FIG. 5, andthe preform is further expanded fully within the cavity of the blow mold25 by blowing air therein so that a cup 28 is molded.

This cup 28 is removed, after the mold has been opened, above the baseplate together with the blow core 24 by the action of attraction, asshown in FIG. 6, and the cup 28 is further fallen onto a transfer member29 inserted underside of the cup and ejected out of the machine.

INDUSTRIAL APPLICABILITY

As described above, according to this invention, the base plate isplaced on the machine bed, the peripheral edge thereof is secured to themachine bed and the interior of the machine bed is utilized as anoperating space. Therefore, the molding machine of this inventionbecomes rigid as compared with the conventional construction which has alimitation in support of the base plate, and even if the load of thebase plate should increase, there occurs no influence on the supporting.Thereby the base plate as well as other devices may be made to have alarge size for an increase in productivity. Furthermore, since the baseplate is secured to the machine bed, fixation of the base plate may befacilitated as compared with the case where the tie bars are used toprovide supporting, and in addition, the supporting structure may besimplified. Thus the molding machine of this invention is applied as theoptimum injection blow molding machine.

What is claimed is:
 1. An injection blow molding machine comprising acircular rotary disk rotatably mounted on an underside of a base plate,said rotary disk being connected to an intermittently rotating anddriving device installed on a central portion of said base plate, arequired number of hold molds also serving as a mold for molding a mouthportion of a container, said hold molds being provide at regularintervals on the undersurface of said rotary disk, a clamping device foran injection mold and a clamping device for a blow mold, each saidclamping device provided at stop positions of said hold molds so thatsaid clamping devices are located vertically above and below the baseplate, characterized in that said rotary disk is placed on the uppersurface of a machine bed with peripheral portions of said rotary diskfixed to said machine bed fixed, and an interior of the machine bedformed into a molding operating space to accommodate therein a lowerclamping mechanism of each of said clamping devices.
 2. The injectionblow molding machine according to claim 1 wherein said clamping devicefor the blow mold comprises, an upper clamping plate inserted movably upand down into a required number of guide rods stood upright on the baseplate, an upper clamping mechanism provided with a clamping cylinderhaving a rod connected to said upper clamping plate, a lower fixed plateprovided over four tie bars suspended within the machine bed fromopposite edges of said rotary disk, and a lower clamping mechanismprovided with a lower clamping device which is inserted into said tiebars a plurality of second guide rods stood upright on said lower fixedplate and of a ram a second clamping cylinder provided on said fixedplate being connected to an underside of said lower clamping plate. 3.The injection blow molding machine according to claim 1 wherein saidupper clamping plate comprises a blow core provided with a stretchingrod, said blow core positioned within a mold portion of said hold moldfrom a hole formed in said base plate and rotary disk.
 4. The injectionblow molding machine according to claim 1 wherein two sets of saidclamping devices are alternately provided in positions in which the holdmolds stop, and injection devices being horizontally opposedly providedon each injection mold clamping device.
 5. The injection blow moldingmachine according to claim 2 wherein said upper clamping plate comprisesa blow core provided with a stretching rod, said blow core positionedwithin a mold portion of said hold mold from a hole formed in said baseplate and rotary disk.
 6. The injection blow molding machine accordingto claim 2 wherein two sets of said clamping devices are alternatelyprovided in positions at which the hold molds stop, and injectiondevices are horizontally opposedly provided on each injection moldclamping device.